Detergent internal combustion engine fuel



United States Patent 9 3,031,278 DETERGENT INTERNA%EI(ZOMBUSTION ENGINE F 4 John P. Bnckmann, Yorba Linda, Francis S. Liggett, Santa Ana, and Edward L. Wiseman, Fullerton, Calif., assignors to Union Oil Company of California, Los Angeles, Calif, a corporation of California No Drawing. Filed Jan. 20 1958, Bar. No. 709,762

13 Claims. (Cl. 44-58) This invention relates to automotive fuels suitable for use in modern high compression spark ignition engines. More particularly the invention relates to gasolines which tend to reduce deposition of objectionable gums and/or carbonaceous materials in carburetors of present day automotive engines. The invention relates further to highly stable gasolines which not only reduce or prevent carburetor deposits but also reduce or prevent the objectionable buildup of deposits normally occurring in intake manifolds, on intake valves and the like without appreciably increasing combustion chamber and exhaust valve deposits.

Modern carburetors suitable for use on present day automobiles are highly developed intricate mechanisms which operate satisfactorily only as long as ports, valves, passages and the like remain free from deposits. It is observed that with many carburetors and particularly 'with multibarrel carburetors, engines often begin to operate in a rough manner after LOGO-5,000 or more miles. The first indication of unsatisfactory operation is generally observed during idling of the engine. When this occurs, or soon thereafter, it is necessary to adjust the carburetor so that the engine will not die when the foot throttle is released. After a few such adjustments the only way to obtain satisfactory operation is to disassemble and clean the carburetor.

The reason for the unsatisfactory operation of engines referred to is that deposits tend to build up at critical points in the carburetor and, as the deposits increase, the ability to adjust the carburetor to compensate for the deposits becomes difiicult. Apparently the most strategic point at which deposits form, i.e., the one which appears to have the greatest effect on idling is the body wall of the carburetor opposite and possibly slightly below the closed or idle position of the throttle plate. In idle position there is normally a certain clearance between the throttle plate and the wall of the carburetor. As carbonaceous deposits build up at this point the clearance becomes less and less for a given setting of the throttle plate and as the clearance is reduced the amount of air going past the throttle plate for a given amount of fuel is greatly reduced and the air-fuel mixture reaching the combustion chamber is much richer than it should be for satisfactory engine operation. It will readily be seen that carburetors in which such deposits have formed must be cleaned before they can satisfactorily perform their intended function.

These carburetor deposits may be due in part to gums present in the gasoline but it is believed that they are due primarily to crankcase vapors venterd from the crankcase, exhaust vapors, dust, smoke, etc. The air cleaner usually employed on automotive engines does not appear to effectively remove these contaminants. Regardless of the theory as tothe source of these deposits it is found that the described deposits occur to the greatest extent in stop and-go city traffic driving where the chances of pulling air contaminated with these vapors into the carburetor are greatest. The relationship between carburetor deposits and crankcase vapors entering the carburetor is more fully described below.

Carburetor deposits are not the only deposits which aifect engine operation. It is observed for example that under certain conditions of operation deposits form to a highly objectionable degree on intake valves, particularly on the fillet or stem side of the valve head, i.e., where the stem joins the head, and enters on the stem area adjacent thereto. These deposits may result from the gasoline or the lubricating oil or more likely both the fuel and the oil contribute to the deposit. The heaviest intake valve deposits have been observed in engines in which multigrade oils are employed. It is thought that the polymerized additive materials employed to give the extremely high viscosity index (V.I.) required in such oils are primarily responsible for these heavy deposits.

Although it is possible to reduce or prevent excessive carburetor deposits by the use of surface active or socalled detergent additives in gasolines, such materials generally tend to increase objectionable deposits in other portions of the induction systems as well as in the combustion chambers, etc., of the engines. Thus While the addition of small amounts of certain metal or non-metal sulfonates, etc., to gasolines has been found to elfectively reduce carburetor deposits, these same additives appear to increase the deposits on intake valves and/ or in combustion chambers and in some cases have been found to cause excessive deposits on exhaust valves. causing improper seating and even resulting in burning of the valves. It is also observed that certain detergent additives have a tendency in some instances to cause corrosion of copper and brass parts in the carburetor. However, this objection can be eliminated by the use of certain combinations of additive materials as will be described hereinbelow.

It is an object of this invention to provide an automotive fuel which will reduce or prevent the formation of objectionable depostis in carburetors.

It is another object of this invention to provide an auto-- motive fuel which prevents carburetor deposits and also prevents the formation of excessive deposits on intake valves and in the combustion chambers of automotive engines.

It is another object of this invention to provide a gasoline suitable for use in modern high compression automotive engines which is stable in storage, which prevents the formation of and/ or removes carburetor deposits, prevents the formation of objectionable deposits in intake ports and on intake valves and does not contribute to combustion chamber deposits to any objectionable degree.

It is still another object or" this invention to provide an additive combination suitable for adding to automotive gasolines, which may contain lead and/or gum inhibitors, which additive combination imparts to the gasoline the ability to prevent or decrease the build-up of deposits in the induction systems of automotive engines.

A more specific object of this invention is to provide gasolines suitable for use in internal combustion engines which gasolines are storage stable, prevent the build-up of carburetor deposits, reduce the tendency for the formation of deposits in other portions of the induction systems and yet do not tend to form exhaust valve deposits.

These and other objects of this invention, which will be apparent as the description thereof proceeds, are attained by adding to gasoline which are deficient in the ability to prevent objectionable carburetor deposits and induction system deposits a certain combination of additives. The additives which cooperate to provide the desired result when added to gasoline in relatively small amounts are a substituted alkylene diamine, a paraflinic lubricating oil and a condensation product obtained by reacting an o-hydroxy aromatic aldehyde with an aliphatic amine containing at least two primary amino groups attached to different carbon atoms of the same open chain.

The substituted alkylene diamines which constitute one of the additives of this invention have the general formula RNH(CH NH wherein R is an aliphatic radical containing between about 12 and about 22 carbon atoms and x is an integer of 2 to 6. Preferably R is a saturated or monoolefinic aliphatic radical or mixture of radicals having from about 14 to 18 carbon atoms and x is 3. Such compounds in which x is 3 and R is an alkyl group derived from a fatty acid are available from the Armour Chemical Division of the Armour Company under the name Duomeens. Duomeen T in which the alkyl group is derived from the fatty acids of tallow is an eminently satisfactory product. Other compounds include Duomeen C, in which the aliphatic group is derived from coconut fatty acids, Duomeen S, in which the aliphatic substituent is derived from soya fatty acids. These compounds and the corresponding compounds in which the aliphatic group is derived from oleic acid, arachidic acid, lauric acid and the like have the ability to prevent or reduce carburetor deposits as described herein. Other compounds which may be used and which fall within the group set forth herein are for example, N-dodecyl ethylene diamine, N-oleyl propylene diamine, and N-oleyl amylene diamine.

Amounts of the substituted diamines to be added to the gasoline will be between about 01 pound and about 70 pounds per 1000 barrels or between about 0.00004% and about 0.02% by weight. Preferably between about 1.0 pound and about pounds per 1000 barrels or between about 0.0004% and about 0.004% by weight will be employed in the gasoline. Smaller amounts of the diamine than those indicated do not appear to have much if any detergent effect as indicated by the build-up of carburetor deposits. On the other hand, amounts of the diamine larger than those indicated are not required in order to completely prevent build-up of deposits at critical points in the carburetor.

The hydrocarbon oil which is to be added to the gasoline to cooperate with the amine in preventing deposits in the induction system of automotive engines is a paraffinic oil of medium to light lubricating oil grade. Although it may be an untreated paraffinc distillate oil providing it is of low wax content it is preferably a solvent treated and dewaxed parafiinc distillate. It will have a viscosity at 100 F. of 200 to 700 SSU, a viscosity index above 70 and an A.P.I. gravity of 32 to 26.5. An ideal hydrocarbon oil to be used will have a viscosity of about 320 SSU at 100 F. and at 210 F. of about 52.2, a V.I. of about 85, a flash point of 445 F. and an A.P.I. gravity of about 28.6. Such an oil is referred to herein as 300 neutral oil and is a solvent treated and dewaxed Western paraflinic mineral oil distillate.

It is essential that the hydrocarbon oil have a viscosity of between about 42 and about 78 SSU at 210 F. since lighter oils do not appear to be effective in reducing or preventing intake valve deposits and heavier oils tend to increase combustion chamber and exhaust valve deposits. Moreover it is desirable that the oil have a flash point of at least about 400 F.

The amount of hydrocarbon oil to be used will be between about 0.02% and about 0.6% by weight of the finished composition. Preferably between about 0.03 and 0.4% by weight of hydrocarbon oil will be employed. An ideal amount is about 0.06% by weight. Although the function of the hydrocarbon oil is to reduce deposits in the induction system, particularly in the intake ports and on intake valves and the like, the manner in which this is accomplished is not known. Possibly a part of the function of the oil is that it acts as a carrier for the diamine and prevents its deposition in the induction system particularly at a point where the fuel is vaporized.

As indicated hereinabove the substituted diamine used alone or with hydrocarbon oil has a tendency to corrode brass parts in the carburetor. Although the amount of corrosion is generally relatively small and is dependent on the amount and type of diamine present, in some instances the amount of corrosion is such as to be definitely objectionable. It is to be noted that the corrosion of brass parts takes place and thus copper is dissolved in the fuel immediately prior to the burning of the fuel. For this reason a gum problem does not generally arise, such as would be expected if the copper was present in the fuel or if the fuel was in contact with copper during periods of storage or while in the automotive fuel tank. The problem here appears to be one of protecting the carburetor parts which are generally made of brass. Such parts include the float and needle seat, idle and high speed jets and the like. Such corrosion is entirely eliminated by adding to the gasoline containing the amine a relatively small proportion of a condensation product of an o-hydroxy aromatic aldehyde with an aliphatic diamine as mentioned above and more fully described herebelow. This condensation product appears to augment the effect of the aliphatic amine in reducing carburetor deposits. This effect is not anticipated since when added to a gasoline which does not contain the amine the condensation product does not have any observable detergent effect.

Suitable metal deactivators which appear to reduce or completely prevent corrosion of brass parts in carburetors due to the presence of the long chain primary amines and which appear to cooperate with the amine in reducing carburetor deposits, are prepared by reacting an aromatic ortho-hydroxy aldehyde with an aliphatic polyamine. Preferably the aliphatic polyamine is an alkylene diamine in which the two amino groups are primary amino groups and are attached to adjacent carbon atoms. Such reaction products are well known and are prepared by condensing salicylaldehyde or alkyl or alkoxy substituted salicylaldehydes with an aliphatic polyamine in the ratio of one mol of aldehyde per primary amine group in the aliphatic polyamine. Thus 2 mols of salicylaldehyde are reacted with 1 mol of an aliphatic diamine. In this description, where the term salicylal is used it is meant to include the alkyl or alkoxy substituted salicylal groups as well as the unsubstituted groups. Compounds which are useful for the purposes set forth thus may represented by the formula where R is an aromatic group in which the OH group is ortho to the CH=N- group and R is a bivalent aliphatic group or a group of the formula in which R" is a bivalent aliphatic group. Examples of such reaction products are disalicylal-ethylene diamine, disalicylal diethylene triamine, disalicylal triethylenetetramine, disalicylal-propylene-diamine, disalicylal-dihexylene triamine, and the like. Thus, as indicated by the above mentioned examples the bivalent aliphatic groups are unsubstituted hydrocarbon groups containing not more than about 6 carbon atoms. As indicated above the aromatic group may have substituents other than the aldehyde and hydroxy groups. Substituents such as alkyl groups, alkoxy groups, and the like may be present and the resulting condensation products are suitable for the purposes mentioned herein. When an alkyl or alkoxy substituted salicylaldehyde is employed the resulting compound will have a formula such as represented above in which R represents an alkyl or alkoxy substituted aromatic hydrocarbon group. A particularly effective product is one prepared by condensing salicylaldehyde with 1,2-diamino-propane.

The amount of such metal deactivator to be used should be between about 0.1 pound and about 3 pounds per 1000 barrels of fuel which corresponds to between about 0.00004% and about 0.0012% by weight of the fuel composition. A particularly suitable amount when 3 to 4 pounds of amine per 1000 barrels of fuel are employed is about 1 pound per 1000 barrels. In general when larger amounts of amine are employed correspondingly larger amounts of the metal deactivator will be used'and when smaller amounts of amine are used correspondingly smaller amounts of the metal deactivator will be added to the fuel.

Gasolines or automotive fuels to which the substituted diamine, hydrocarbon oil, and metal deactivator are to be added and in which these additives perform the functions described include substantially all grades of gasoline presently being employed in automotive and internal combustion aircraft engines. Such gasolines may be prepared from saturated hydrocarbons, e.g., straight-run stocks, alkylation products, and the like, with or without gum inhibitors, and with or without soluble lead compounds as for example tetraethyl lead, T.E.L., or ethyl fluid. The gasolines may be made wholly or partially from cracked stocks which stocks may be obtained by thermal and/or catalytic cracking methods. In such case, the gasolines will contain gum inhibitors and may or may not contain T.E.L. Generally automotive and aircraft gasolines contain both straight-run and cracked stocks with or without alkylated hydrocarbons, reformed hydrocarbons and the like. The preparation of straight-run, alkylated, reformed and cracked stocks for blending in the preparation of automotive gasolines, aircraft gasolines, and the like, are well known and need not be further described. Gasolines suitable for use in present day automotive engines with which this invention is primarily concerned will generally have the characteristics shown in Table I and it is primarily to gasolines of the character indicated to which the additives of this invention are added and found to be effective.

B Determined by ASTM Method D-38l. b ASTM Method D-Sti.

The above data were obtained on two commercial gasolines of the grades indicated and are believed to be typical of commercial gasolines marketed at the present time. These gasolines contain 23 ml. of ethyl fluid per gallon and 5 to pounds .of a phenolic type gum inhibitor per 1000 gallons. It is to be pointed out that the usefulness of the additives of this invention is not limited to gasolines .of the types indicated as would be understood in the art. The same additives are effective in gasolines of lower or higher volatility as well as gasolines having lower or higher knock rating, many of which gasolines are presently commercially available. Suitable gasolines may contain as much as about 5 ml. of tetraethyl lead per gallon, such amounts being used commercially in aviation gasolines. Gasolines which contain gum inhibitors may contain single materials Or combinations of inhibitors. The use of gum inhibitors is well known in the art and need not be further described. It might be pointed out that the inhibitors are generally aromatic compounds containing amino and/ or hydroxyl groups and it should be mentioned further that the particular gum inhibitor or inhibitors employed does not appear tohave any appreciable effect on the ability of the described additive combination to perform the functions described herein. When gum inhibifrom about 5 to about pounds per 1000 barrels.

The substituted diamines, hydrocarbon oil and the metal deactivator are all soluble in gasoline, and preparation of gasolines containing small amounts of these materials presents no unusual blending problems. If desiredone or more of the additive materials may be dissolved in small amounts of the gasoline and the concentrate thus obtained added and mixed with the gasoline. In the case of metal deactivator, compounds of this sort are obtainable from suppliers and in such case they are generally obtained as an solution in an aromatic solvent such as toluene or Xylene.

Various tests have been used to determine the effect of the additives of this invention in improving the characteristics of gasoline in respect to their ability to reduce or prevent carburetor deposits and deposits in other portions of the induction systems of spark ignition internal combustion engines. These tests and the results obtained with these tests are described below.

Detergency Test A test designed to show the ability of a fuel to prevent the formation of deposits in throat or throttle sections of carburetors has been developed and used in order to determine the effectiveness of various detergent additives in preventing such deposits. In this test conditions present in the throat of a carburetor have been simulated in that gasoline, air and exhaust from an engine are pulled into a glass chamber by means of suction, entry to the chamber being through a slot 1 inch long and 0.012 inch wide located in such a position that the gasoline, air and exhaust gases impinge on and pass downward over the surface of a l'by 2.5 inch strip of bright aluminum foil. Because of partial vacuum in the chamber vaporization of the liquid fuel occurs in the same manner as it does in a carburetor. The aluminum strip simulates and in fact corresponds to the walls of a carburetor throat.

In the test the gasoline is fed by gravity at the rate of 40 ml. per minute to the slot above referred to. Vacuum is applied to the chamber to pull air and fuel downward over the test strip. Air entering the chamber is contaminated with the exhaust gases produced by a one cylinder, one horsepower gasoline engine operated with a rich fuel mixture. The exhaust from this engine is passed through three knock-out chambers so as to separate and remove all materials present in the exhaust which are liquid at ordinary temperatures.

In carrying out this test in the simulated carburetor throat, after the test strip is wet with gasoline, air contarninated with exhaust is pulled into the chamber and passed in contact with the aluminum strip. Gasoline, at the rate indicated above is permitted to flow down the aluminum strip for a period of two minutes then the supply is shut off for two minutes. This cycle is repeated 4 times, the total time of test being 16 minutes. At the end of the test the amount of deposit on the aluminum test strip is evaluated visually. The proportion of the area of the strip stained with deposits is determined and the relative thickness of the deposit is estimated by Observing blackness of the deposit. A :very thin coating is greyish due to the fact that the metal shows through the deposit. As the deposit becomes thicker it appears blacker. The deposits are rated on a scale of 1 to 10, where 10 represents a strip completely free of deposits and 1 represents a test strip substantially completely covered with black deposits. So that variations in conditions of operation are not reflected in test results, blank runs are made at close intervals. Thus the base gasoline to which additives being tested are added will be run at the start of a period of tests and run again at intervals to be sure that conditions of operation are maintained such that comparable results are obtained in a series of tests.

The following Table II shows the results of tests on gasolines with and without the additives of this invention. All percentages are given in percent by weight.

7 TABLE II Detergent-y Test No. Composition Base fuel b Fuel N0. 1 plus 0.00l4%-Duomeen S 0.00%

300 neutral oil, 0.0004% disalicylal-l,2propylene diamine.

Fuel No. 1 plus 0.0007% Duomeen C 0.03% 8 300 neutral oil, 0.0002% disalicylal-1,2-prpylene diamine.

Fuel No. 1 plus 0.0028% Duomeen C 0.06%

300 neutral oil, 0.001% disalicyla1-1,2-propylene diamine.

Fuel No. 1 plus 0.00147' Duomeen T 0.12% 9 300 neutral oil, 0.0004% disalicylal ethylene diamine.

Fuel No. 1 plus 0,0014% N-oleyl propylene 9- diamine, 0.00% 300 neutral oil, 0.0004% disalicylal-1,2'propylene diamine.

Fuel No. 1 plus 0.0014% Duomeen C d 9- Fuel No. 1 plus 0.0004% disalicylal-l,Z-propylene 2 diamine.

Fuel N o. 7 plus 0.00047, dlsalicylal-l,2-propylene 9+ diamlne.

Fuel No. 9 plus 0.06% 300 neutral oil 9+ n Rated on a scale of 1 to where 10 represents a strip completely free of deposits and 1 a strip substantially completely covered with deposits.

A commercial premium gasoline of 87/98 octane rating containing straight-run and catalytically cracked hydrocarbon base stocks, 2.95 ml. of lead per gallon and 0.005% of a phenolic type gum inhibitor.

:flR-N H(OH2) N H R=alkyl radicals derived from soya fatty ac s.

f d Forninila as in footnote 0 but R=alkyl radicals derived from coconut atty ac s.

a Formula as in footnote c but R=alkyl radicals derived from tallow fatty acids.

It will be seen that the base fuel, i.e., the gasoline without substituted diamine, oil or metal deactivator has a very low detergency. Fuels having all three of these additives, i.e. fuels Nos. 2 to 6 and 10 all have exceptionally high detergency. Fuel No. 7 with just the substituted diamine has very good detergency but the addition of metal deactivator to it, fuel No. 9, improves the detergency whereas the addition of metal deactivator alone to the base fuel, fuel No. 8, fails to improve the detergency. Moreover the addition of mineral oil appears to have no effect on the detergency in this test.

It is to be pointed out that the results presented in the table are typical of those obtained with other substituted diamines described herein and other metal deactivators described herein. All such compounds falling Within the groups of compounds described when added to gasolines such as were shown to be used in the above tests as Well as other gasolines with or without lead or gum inhibitors, or the like, perform the function of improving greatly the deter-gency of the fuel.

Carburetor Deposit Test This is an accelerated engine test used to determine the effectiveness of gasolines to prevent buildup of deposits in carburetors.

A 1955 Oldsmobile V-8 engine is used for the test. The standard four barrel carburetor is used, however only two barrels of the carburetor are used because of low speed operation. A flexible, 1' LD. metal tube is run from the breather pipe to the intake of the air cleaner which is an oil bath air cleaner from which the oil has been removed. Also air is pumped into the crankcase at the rate of 0.1 cu. ft. per minute. The engine is 0perated seconds at 1500 r.p.m. and then 45 seconds at 450 r.p.m., and this cycle is repeated for 44 hours. During the higher speed the engine is operated under a 30 pound load and 11.25 brake horsepower. The coolant temperature out is maintained at 165:5 F. and the air/fuel ratio is 12 to 13/1 throughout the test. A noncornpounded SAE paraflinic oil is used in the crankcase.

At the end of the 44 hour test the carburetor is rated for depositson the curtain area below the butterfly valve and the ridge which for purposes of this description is ridge of deposit which forms as a circular deposit immediately below the butterfly valve when it is in its closed position. The rating is done on a scale of 1 to 10 where 10 represents a completely clean area and 1 represents deposits present over the entire area being rated.

Following this rating the two barrels of the carburetor are washed with a light petroleum naphtha to remove naphtha soluble materials, the deposits are then removed by scraping, dried in an oven at C. to constant weight and then weighed. The total weight of deposit from both barrels is recorded as the weight of a deposit in this test.

Table III gives the results of carburetor deposit tests on gasolines with and without the additives of this invention.

TABLE III Carburetor Deposit Test Fuel Detergcncy Deposit Ratings 1 wt., Grains No. Composition Curtain Ridge 1 Base fuel b 0.031 2.7 4.0 2 Fuel No.1 plus 0.0014% Duomeen S 0.06% 300 neutral oil, 0.0004% disalicylal-l,Z-propylene dia- Inine. 0.010 6.2 0. 4 3 Fuel N o. 1 plus 0.0007% Duomeen 0. 004 7.6 7.0

C 0.08% 300 neutral oil, 0.0002% disalieylal-l,-2-propylene diamine. 4 Fuel No. 1 plus 0.0014% Duomeen 0.003 8.0 7. 2

T 0.067 300 neutral oil, 0.0004% disalicylal ethylene diamine. 5 Fuel No. 1 plus 0.00l4% N-oleyl 0.008 7.0 7.3

propylene diaminc. 6 Fuel No. 5 plus 0.0004% disalicy- 0.006 7.8 8.0

1all,2-propylene diamine. 7 Fuel No. 1 plus 0.0004% disalicy- 0.032 3.0 3.9

lal-l,2-propylcne diamine. 8 Fuell No. 6 plus 0.06% 300 neutral 0. 006 7. 7 8.1

a Rating scale is from 1 to 10 where 10 represents a completely clean area and 1 represents deposits present over entire area being rated.

b A commercial premium gasoline of 87/98 octane rating containing straight-run and catalytically cracked hydrocarbon base stocks, 2.95 ml. of lead per gallon and 0.005% of a phenolic type gum inhibitor.

0 R-NH-(C H2)3-N Hz, R =alkyl radicals derived from soya fatty acids 4 Formula as in footnote 1; but R=alkyl radicals derived from coconut fatty acids.

6 Formula as in footnote 1) but R=alkyl radicals derived from tallow fatt} acids.

The data presented in Table III show that the substi-tuted diamines of this invention greatly reduce the weight of carburetor deposits and improve the detergency of gasolines containing them. They show also that the metal deactivators, althoug having substantially no effect on deposits or detergency when used alone, do have a synergistic effect when used in combination with the substituted diamines.

It is to be pointed out that although Table III shows data on representative substituted diamines and metal deactivators, other compounds of each of these classes as defined herein produce equivalent results in the tests used.

Road Load Detergency Test This test is run in a standard six cylinder 1952 Chevrolet 216 cubic inch automobile engine with a standard carburetor and is used to determine the relative amounts of deposits on intake valves, which valves operate relatively dry, i.e., without oil flooding, using various fuels. The engine is operated for 40 hours at 2500 r.p.m. with a load of 20 brake horsepower. Cooling water is circulated through the cooling system of the engine at a rate such that with F. water entering the engine, the water leaving the engine is F. :5 F. The oil is maintained at a temperature of F. i5 F.

Following completion of the 40-hour run the intake valves are removed, the surfaces of the valves facing the combustion chamber are scraped and/orbuifed free of deposits and the valves are then washed with naphtha to remove naphtha-soluble materials. The amounts of naphtha-insoluble deposits on the fillet and adjacent stem area is determined by weighing. This test, although it does not give absolute values, does give comparative data from which the efiectiveness of various gasoline additives in preventing or reducing deposition on intake valves can be evaluated. The results are reported as naphthainsoluble deposits per 6 valves.

In this test it is believed that the deposits are largely from the fuel rather than the crankcase oil. This conclusion is reached since the intake'valves operate with a minimum of lubrication and therefore very little crankcase oil reaches the valve tulips. The data shown in the following Table IV were all obtained using and SAE 20 heavy duty crankcase oil. The only variations were in the fuel employed.

TABLE IV Road Load Detergency Test PART 1 Fuel Naphtha Insoluble, Intake Valve Deposits, No. Composition Average,

grams/valve 1-.- Base fuel a 0.250 2 Commercial Premium Gasoline b 0.610

PART 2 3 Fuel N o. 1 plus 0.00l4% Duomeen T, 0.00% 0.30

300 neutral oil, 0.0004% disalicylal-1,2- propylene diamine. 4 Fuel No. 1 plus 0.0028% Duomeen C 0.06% 0.33

300 neutral oil, 0,0008% disalieylal-1,2- propylene diamine. 5 Fuel N o. 1 plus 0.0014% N-oleyl propylene 0.28

diamine, 0.06% 300 neutral oil, 0.0004% disalicylal ethylene diamine. 6 Fuel No. 1 plus 0.0014% Duorneen S 0.12% 0.26

300 neutral oil, 0.0002% disalicylal ethylene diamine. 7 Fuel No. 1 plus 0.0014% Duomeen S 0.75 8 Fuel N o. 7 plus 0.06% 300 neutral oil 0.27

a A commercial premium gasoline of 87/98 octane rating containing straight-run and eatalytically cracked hydrocarbon base stocks, 2.95 ml. of lead per gallon and 0.005% of a phenolic type gum inhibitor.

b A commercial gasoline of 97 knock rating containing lead, gum inhibitor and a detergent additive.

See footnote 0 of Table II.

See footnote d of Table II.

a See footnote 0 of Table II.

Part 1 of Table IV shows that whereas a premium gasoline which does not contain additives other than the conventional additives such as tetraethyl lead and gum inhibitor permits the formation of but relatively small amounts of intake valve deposits, a commercial gasoline containing detergent additive gives relatively large amounts of such deposits.

In Part 2 of the table the addition of substituted diamine is shown to permit the formation of intake valve deposits. Addition of 300 neutral oil, a medium viscosity parafiinic mineral lubricating oil causes an appreciable decrease in the amount of deposit. Moreover, the additive combination described herein produces fuels of excellent detergency characteristics as indicated by data presented in Tables II and III and yet causes only a negligible increase in intake valve deposits.

The above description and examples of our invention are illustrative of the broader aspects of this invention class HORCH=N-R'N=CH-ROH in which R is a member selected from the group consist- .ing of aromatic hydrocarbon groups, alkyl substituted aromatic hydrocarbon groups and alkoxy substituted aromatic hydrocarbon groups in which the OH group is ortho to the -CH=N group and R is a group of the consisting of bivalent aliphatic groups and -R"-NH-R"--groups in which R" is a bivalent :aliphatic group, all of said bivalent aliphatic groups being unsubstituted hydrocarbon groups containing not more than about 6 carbon atoms.

2. The internal combustion engine fuel according to claim 1 in which said substituted diamine has the formula in which R is derived from soya fatty acids and x is 3.

3. The internal combustion engine fuel according to claim 1 in which said substituted diamine has the formula in which R is derived from tallow fatty acids and x is 3.

4.'The internal combustion engine fuel according to claim 1 in which said substituted diann'ne is N-oleyl propylene diamine.

5. The internal combustion engine fuel according to claim 1 in which said last named compound is disalicylal- I 1,2-propylene diamine.

6. An internal combustion engine fuel consisting essentially of hydrocarbons in the gasoline boiling range containing between about 0.0004% and about 0.004% by weight of a substituted diamine of the formula RNH( CH -NH in which R is an aliphatic hydrocarbon radical containing between about 12 and about 22 carbon atoms and x is an integer of 2 to 6; between about 0.03% and 0.4% by Weight of a parafiinic hydrocarbon oil having a viscosity at 210 F. between 42 and 78 SSU and a flash point of at least 400 F., and between about 0.0000 1% and about 0.00-l2% by weight of a compound of the formula in which R is a member selected from the group consisting of aromatic hydrocarbon groups, alkyl substituted aromatic hydrocarbon groups and alkoxy substituted aromatic hydrocarbon groups in which the OH group is ortho to the -CH=-Ngroup and R is a group of the class consisting of bivalent aliphatic groups and groups in which R" is a bivalent aliphatic group, all of said bivalent aliphatic groups being unsubstituted hydrocarbon groups containing not more than about 6 carbon atoms.

7. An internal combustion engine fuel consisting essentially of hydrocarbons in the gasoline boiling range and containing up to 5 ml. of tetraethyl lead per gallon; between about 5 and about 25 pounds per 1000 barrels of a phenolic type gum inhibitor; between about 0.00004% and about 0.02% by weight of a substituted diamine of the formula in which R is an aliphatic hydrocarbon radical containing between about 12 and about 22 carbon atoms and x 1 1 is an integer of 2 to 6; between about 0.02% and about 0.6% by weight of a paralfinic hydrocarbon oil having a viscosity at 210 F. between about 42 and about 78 SSU and a flash point of at least 400 F.; and between about 0.00004% and about 0.0012% by weight of a compound of the formula in which R is a member selected from the group consisting of aromatic hydrocarbon groups, alkyl substituted aromatic hydrocarbon groups and alkoxy substituted aromatic hydrocarbon groups in which the OH group is ortho to the --CH=N group and R is a group of the class consisting of bivalent aliphatic groups and -R-NHR"- groups in which R" is a bivalent aliphatic group, all of said bivalent aliphatic groups being unsubstituted hydrocarbon groups containing not more than about 6 carbon atoms.

8. The internal combustion engine fuel according to claim 7 in which said gum inhibitor is an alkyl substituted phenol.

9. An internal combustion engine fuel consisting essentially of hydrocarbons in the gasoline boiling range containing between about 0.0004% and about 0.004% by weight of a substituted diamine of the formula in which R is an aliphatic radical derived from a fatty acid containing between about 12 and about 22 carbon atoms and x is 3; between about 0.03% and about 0.4% by weight of a paraffinic hydrocarbon oil having a viscosity at 210 F. between 42 and 78 SSU and a flash point of at least 400 F.; and between about 0.00004% and about 0.0012'% by weight of disalicyla1-1,2-propylene diamine.

10. An internal combustion engine fuel consisting essentially of hydrocarbons in the gasoline boiling range containing up to m1. of tetraethyl lead per gallon; between about 5 and about 25 pounds per 1000 barrels of a phenolic type gum inhibitor; between about 0.0004% and about 0.004% by weight of a substituted diamine of the formula in which R is an aliphatic radical derived from a fatty acid containing between about 12 and about 22 carbon atoms and x is 3; between about 0.03% and about 0.4% by weight of a paraffinic hydrocarbon oi lhaving a viscosity at 210 F. between 42 and 78 SSU and a flash point of at least 400 F.; and between about 0.00004% and about 0.0012% by weight of disalicylal-l,2-propylene diamine.

11. An internal combustion engine fuel consisting essentially of hydrocarbons in the gasoline boiling range containing up to 5 ml. of tetraethyl lead per gallon; between about 5 and about 25 pounds of a phenolic type gum inhibitor per 1000 barrels; between about 0.0004% and about 0.004% by weight of a substituted diamine of the formula in which R is an alkyl radical derived from a fatty acid of 14 to 18 carbon atoms and x is 3; between 0.02% and 0.6% by weight of a parafiinic hydrocarbon oil having a viscosity at 210 F. between about 42 and about 78 SSU and a flash point of at least 400 F.; and between about 0.0000 1% and about 0.0012% by weight of disalicylal-1,2-propylene diamine.

12. The internal combustion engine fuel according to claim 11 in which said fatty acid is a mixture of coconut fatty acids.

13. The internal combustion engine fuel according to claim 11 in which said fatty acid is a mixture of soya fatty acids.

References Cited in the file of this patent UNITED STATES PATENTS 2,312,790 Backoif et a1 Mar. 2, 1943 2,367,815 Williams et al. Jan. 23, 1945 2,646,348 Neudeck July 21, 1953 2,736,658 Pfohl Feb. 28, 1956 2,768,884 Bowers Oct. 30, 1956 2,771,348 Meguerian Nov. 20, 1956 2,789,891 Brandes et al. Apr. 23, 1957 2,839,373 Barusch et a1. June 17, 1958 2,891,850 Cosgrove et a1 June 23, 1959 2,906,611 Schnaith et al Sept. 29, 1959 

1. AN INTERVAL COMBUSTION ENGINE FULE CONSISTING ESSENTIALLY OF HYDROCARBONS IN THE GASOLINE BOILING RANGE CONTAINING BETWEEN ABOUT 0.00004% AND ABOUT 0.02% BY WEIGHT OF A SUBSTITUTED DIAMINE OF THE FORMULA 